Draft: Update/Refactor bb-ci Dockerfile

Closes https://repo1.dso.mil/platform-one/big-bang/pipeline-templates/pipeline-templates/-/issues/68

Changes

• Added Kyverno cli to bb-ci Dockerfile

• Added a requirements.txt file to improve visibility/discoverability for managing Python package dependencies

• Removed unused tooling (istioctl, flux, argo, etc)

• Update versions for multiple tools

  • k3d, helm, kubectl, and kustomize are notable tools that were updated

• Refactor Dockerfile to use multi-stage build approach

Tests

• Verified Big Bang pipelines are good with updated 2.5.2 image